Deformable seat shell with motion control

ABSTRACT

A seat assembly includes a seat bottom with a deformable seat shell. The deformable seat shell is configured to change shape with a changing occupant load distribution. The seat shell is coupled with a support frame via a shell motion controller having one or more motion control links. Each motion control link is coupled with the seat shell at a fixed location relative to the seat shell and with the support frame at a fixed location relative to the support frame. The shell motion controller allows these fixed locations to move relative to each other and also constrains their relative movement. The combined seat shell deformation and controlled movement relative to the support frame can provide the seat occupant with a comfortable seating experience while preventing pelvis drift and potentially eliminating traditional foam seat cushions.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims the benefit of U.S. Provisional Ser. No.61/652,058 filed on May 25, 2012, the entire contents of which areincorporated herein by reference.

TECHNICAL FIELD

The present disclosure relates to a seat assembly and, in particular, toa seat assembly having a variable shape.

BACKGROUND

Seat assemblies, such as vehicle seats, often include a generallyhorizontal seat bottom and a generally upright seat back. Each of theseat bottom and seat back usually includes an underlying structure, adecorative covering material, and a foam bun or cushion between thestructure and covering material. The foam cushion is softer than theunderlying structure and is intended to provide a comfortable seatingsurface for a seat occupant. Such cushions may be configured to compresswhen the seat occupant is seated. Foam density, thickness, composition,and porosity may affect the overall feel of the seat. Traditional foammaterials, such as polyurethane foam, are thermoset materials and maypose end-of-life difficulty with respect to dismantling and materialrecycling.

U.S. Patent Application Publication No. 2013/0088061 describes a seatassembly with a collapsible cushion support assembly disposed on a seatbottom frame. The collapsible cushion support assembly is configured tosupport a seat occupant when not collapsed. The seat assembly isconfigured so that the cushion support assembly collapses to a locationcloser to the vehicle floor when the seat back is folded down over theseat bottom to reduce the overall height of the folded seat assembly.

SUMMARY

In accordance with one or more embodiments, a seat assembly includes aseat bottom having a deformable seat shell configured to change shapewith a changing occupant load distribution, a seat back coupled to andextending from the seat bottom, and a motion control link coupling thedeformable seat shell with a support frame via a frame joint and a shelljoint so that the joints can undergo relative movement. The frame jointis at a fixed position relative to the support frame, and the shelljoint is at a fixed position relative to the deformable seat shell. Themotion control link constrains the relative movement.

In accordance with one or more embodiments, the motion control link is aspring that undergoes elastic deformation when the joints undergorelative movement.

In accordance with one or more embodiments, the seat assembly includes acam surface, and the motion control link elastically bends along the camsurface when the joints undergo relative movement.

In accordance with one or more embodiments, the seat assembly includes acam surface that is fixed with respect to the support frame or withrespect to the deformable seat shell.

In accordance with one or more embodiments, the seat assembly includes acam surface and a layer of sound-attenuating material located betweenthe motion control link and the cam surface when the motion control linkelastically bends along the cam surface.

In accordance with one or more embodiments, the seat assembly includes afirst cam surface located on one side of the motion control link and asecond cam surface located on an opposite side of the motion controllink. The motion control link elastically bends along both cam surfaceswhen the joints undergo relative movement.

In accordance with one or more embodiments, at least one of the jointsis a constrained joint.

In accordance with one or more embodiments, the motion control link isan elongate member extending along a front-to-rear direction withrespect to the seat assembly.

In accordance with one or more embodiments, the motion control link isan elongate member extending along a side-to-side direction with respectto the seat assembly.

In accordance with one or more embodiments, the motion control link is aflat spring.

In accordance with one or more embodiments, the motion control link is aflat spring, and the direction of the width of the flat spring isinclined with respect to horizontal.

In accordance with one or more embodiments, a second motion control linkcouples the deformable seat shell with the support frame via a secondframe joint and a second shell joint so that the second joints canundergo relative movement. The second frame joint is at a fixed positionrelative to the support frame, and the second shell joint is at a fixedposition relative to the deformable seat shell. The second motioncontrol link constrains the relative movement of the joints.

In accordance with one or more embodiments, the motion control link(s)include at least one bolster spring that bends along an upward facingcam surface and a downward facing cam surface when the deformable seatshell and the support frame undergo relative movement.

In accordance with one or more embodiments, the motion control link(s)include at least one cross-spring that bends along an inclined camsurface so that the deformable seat shell moves in downward and rearwarddirections relative to the support frame when an occupant sits on theseat assembly.

In accordance with one or more embodiments, the deformable seat shellincludes left and right leg support sections separated by a centrallylocated slot that allows the left and right leg support sections tosimultaneously deform by different amounts from each other.

BRIEF DESCRIPTION OF THE DRAWINGS

Preferred exemplary embodiments will hereinafter be described inconjunction with the appended drawings, wherein like designations denotelike elements, and wherein:

FIG. 1 is a perspective view of an embodiment of a seat assembly in theform of a vehicle seat including a deformable seat shell and a shellmotion controller, shown without a decorative covering;

FIG. 2 is a schematic side view of outer motion control links in anunloaded condition;

FIG. 3 is a schematic side view of the outer motion control links ofFIG. 2 in a loaded condition;

FIG. 4 is a schematic side view of inner motion control links in anunloaded condition;

FIG. 5 is a schematic side view of the inner motion control links ofFIG. 4 in a loaded condition;

FIG. 6 is an exploded view of a portion of the seat assembly of FIG. 1;

FIG. 7 is a schematic side view of an embodiment of the seat assemblywith a seat occupant sitting thereon;

FIG. 8 is a schematic side view of a seat assembly illustrating pelvisdrift;

FIG. 9 is a schematic front view showing various shapes of a singledeformable seat shell under various loading conditions due to variousoccupant sizes;

FIG. 10 is a front bottom perspective view of a portion of anotherembodiment of the seat assembly including a deformable seat shell and ashell motion controller;

FIG. 11 is a front top perspective view of the portion of the seatassembly of FIG. 10;

FIG. 12 is an exploded view of the portion of the seat assembly of FIG.10;

FIG. 13 a schematic side view of the outer motion control links of FIGS.10-12 in an unloaded condition;

FIG. 14 is a schematic side view of the outer motion control links ofFIG. 13 in a loaded condition;

FIG. 15 is a schematic perspective view of the inner motion controllinks of FIGS. 10-12 in an unloaded condition;

FIG. 16 is a schematic cross-sectional view of the inner motion controllinks of FIG. 15 in a loaded condition;

FIG. 17 is a front bottom perspective view of an embodiment of thedeformable seat shell, illustrating the attachment of cross-spring cams;

FIG. 18 is a bottom perspective view of an embodiment of an outersupport structure, illustrating the attachment of bolster springs;

FIG. 19 is perspective view of a support frame, illustrating theattachment of cross-springs;

FIG. 20 is a perspective view of the support frame of FIG. 19,illustrating the attachment of bolster spring subassemblies;

FIG. 21 is a perspective view of the subassembly of FIG. 17 attached tothe subassembly of FIG. 20; and

FIGS. 22-28 illustrate various examples of deformable seat shellssuitable for use with the shell motion controller described herein.

DETAILED DESCRIPTION

The seat assembly described herein employs a deformable seat shell thatis configured to change shape with a changing occupant loaddistribution. The deformable seat shell may be coupled with a supportframe via one or more motion control links configured to allowconstrained relative movement between the frame and shell components.The combination of the deformable seat shell and its constrainedrelative movement with respect to the support frame can provide the seatoccupant with a comfortable seating experience in both the short-termand long-term, while preventing pelvis drift and potentially eliminatingtraditional foam seat cushions. The resulting seat assembly isself-adjustable, conforming to the shape and size of the seat occupant,not only when first seated, but also when the seat occupant's weight,position, and/or posture changes while seated. Thus, the movement of theseat occupant can be the primary input that adjusts the seat assemblyfor comfort so that the seat occupant does not have to search for themost comfortable seating configuration through trial and error withmultiple seat adjustments mechanism. While described below in thecontext of illustrative embodiments of vehicle seats, the teachingspresented herein are applicable to any seat assembly, including officechairs, theatre seating, home furnishings, or any other type of seating.

FIG. 1 illustrates one embodiment of the seat assembly 10 in the form ofa vehicle seat, shown without a decorative covering or trim. Thedouble-headed arrows in FIG. 1 indicate frontward and rearwarddirections (F and R), as well as left and right directions (L and R).The seat 10 includes a seat bottom 12 and a seat back 14 coupled to andextending from the seat bottom, in an upward direction in thisembodiment. The illustrated seat back 14 includes a backrest portionextending from the seat bottom and a headrest portion extending from anopposite end of the backrest. The seat bottom 12 includes a deformableseat shell 16 configured to change shape with a changing occupant loaddistribution. A changing occupant load distribution occurs when a personfirst sits on or vacates the seat assembly, when a seat occupant shiftshis or her weight, position and/or posture, or when inertial forcescause the weight of the seat occupant to be distributed differently,such as during vehicle speed-changing or turning maneuvers or during acollision, where the seat assembly is a vehicle seat. The deformableshell 16 may be monolithic (formed from a single piece of material) oran assembly of components. In one embodiment, the deformable shell 16 isformed from a plastic material with a plurality of slots 18 formedthrough the thickness of the material, as shown in the example ofFIG. 1. The slots 18 provide an otherwise semi-rigid plastic shape withshape-changing flexibility so that the deformable shell 16 can bend,flex, twist or otherwise change shape in response to changes in the loadand/or load distribution applied thereto.

The exemplary deformable seat shells shown as line drawings in theaccompanying figures are merely impressional representations orsuggestions of overall appearance. For example, the illustrateddeformable seat shells include large numbers of slots with complexthree-dimensional shapes that are difficult to represent as linedrawings in two-dimensions. Thus, many of the seat shell slots in theline drawings are represented without slot ends and/or are representedas lines only to indicate contour and/or location. Reference is made toFIGS. 22-28 for examples of deformable seat shells that have beenconstructed for shape-changing and constrained movement by one or moremotion control links as described herein. The example of FIG. 22includes a plurality of slots formed therethrough. Some of the slots arelocated along the top of the shell and extend laterally (left-and-right)from a central portion of the shell and partially down sidewalls of theshell. Other larger slots, fewer in number, are located along the top ofthe shell in the central portion of the shell where a seat occupantwould sit. The example of FIG. 23 includes a similar arrangement ofslots in the central portion with the left and right portions havingslots with a slight S-shape as they extend from the central portion tothe sidewalls. FIGS. 22-28 are examples of various other deformable seatshells that can be supported with constrained movement by one or moremotion control links as described below. Any other configuration capableof shape-changing movement in response to changes in the load and/orload distribution applied to the seat shell is possible.

Referring again to FIG. 1, a shell motion controller 20 couples thedeformable seat shell 16 with a support frame 22 so that the deformableshell and the support frame can undergo constrained relative movement.The shell motion controller 20 includes one or more motion control links24, 26. In this particular example, the shell motion controller 20includes a plurality of motion control links, including outer motioncontrol links 24 and inner motion control links 26. Each of the motioncontrol links 24, 26 couples the deformable seat shell 16 with thesupport frame 22 via a frame joint 28 and a shell joint 30. Each framejoint 28 has a fixed position relative to the support frame 22, and eachshell joint 30 has a fixed position relative to the deformable seatshell 16. Each motion control link 24, 26 has a corresponding framejoint 28 and shell joint 30 and allows the pair of joints to move withrespect to each other while also constraining their relative movement.

In the illustrated embodiment, each motion control link 24, 26 is aspring that undergoes elastic deformation when the corresponding frameand shell joints 28, 30 undergo relative movement. Each of theillustrated outer motion control links 24 is an elongate memberextending along the front-to-rear direction with respect to the seatassembly. More particularly, each of the illustrated outer motioncontrol links 24 is a strip of material (i.e., a flat spring) that bendsin a direction parallel with the direction of the thickness of the stripof material (i.e., up and/or down) when the corresponding joints 28, 30undergo relative movement. Frame and shell joints 28, 30 are located atopposite ends of each outer motion control link and are constrainedjoints in this example. As used herein, a constrained joint is a jointwith zero degrees of freedom. This use of “constrained” is not to beconfused with the constrained relative movement of the frame and shelljoints 28, 30. In the context of relative movement, “constrained”indicates that the distance between the joints 28, 30 is limited by someother component or attribute (such as the length of the correspondingmotion control link). Other types of joints include a pivot joint (onerotational degree of freedom), a sliding joint (one linear degree offreedom, and a ball joint (two rotational degrees of freedom), forexample. Constrained joints can be formed using a fastener, weld,adhesive or other means and may also include flanges, ribs, brackets, orother features intended to limit the relative movement between joinedcomponents.

The outer motion control links 24 shown in FIG. 1 may also be referredto as bolster springs, as they are located along the left and rightsides of the seat assembly to support the side bolster regions of theseat bottom 12. Each of the bolster springs 24 is configured toelastically bend along at least one cam surface 32, 34 when thecorresponding joints 28, 30 undergo relative movement. In particular,each of the illustrated bolster springs 24 bends along an upward facingcam surface 32 and a downward facing cam surface 34. In this example,the upward facing cam surface 32 is fixed in position relative to thesupport frame 20, and the downward facing cam surface 34 is fixed inposition relative to the deformable seat shell 16. This motion issubsequently described in greater detail.

Each of the illustrated inner motion control links 26 is also a strip ofmaterial that bends in a direction parallel with the direction of itsthickness. When in an unloaded or relaxed position as shown, theillustrated inner control links 26 are inclined with respect to thehorizontal, extending in both the front-to-rear direction and theup-and-down direction. The corresponding frame and shell joints 28, 30are located at opposite ends of each inner motion control link 26. Inthis case, the shell joint 30 is a pivot joint, and the frame joint (notshown in FIG. 1) is a constrained joint. The inner motion control links26 shown in FIG. 1 may also be referred to as seating region springs, asthey are located to support the seating region located between the sidebolster regions of the seat bottom 12. Each of the seating regionsprings 26 is configured to elastically bend along at least one camsurface (not shown in FIG. 1) when the corresponding frame and shelljoints undergo relative movement. Here, each of the springs 26 bendsalong an upward facing cam surface that is fixed in position relative tothe support frame 20 so that the shell joint 30 moves in both downwardand rearward directions relative to the corresponding frame joint.

FIGS. 2-5 are simplified schematic side views illustrating theconstrained relative motion associated with each of the motion controllinks 24, 26 depicted in FIG. 1. FIG. 2 shows a pair of outer motioncontrol links 24, each with a constrained frame joint 28 at one end anda constrained shell joint 30 at the opposite end. In this case, the pairof outer motion control links 24 is formed from a single piece ofmaterial so that the control links share a frame joint 28, with eachcontrol link extending from the frame joint 28 to individual shelljoints 30. The illustrated pair of motion control links 24 could also beformed as separate components, and each may be configured with a uniquespring rate, shape, joints, etc. FIG. 2 shows the control links 24 in arelaxed or unloaded condition in which they are generally flat. FIG. 3shows the control links 24 after corresponding frame and shell joints28, 30 undergo relative movement, such as when a seat occupant sits onthe seat. Each motion control link 24 bends along upward facing anddownward facing cam surfaces 32, 34, as shown. One effect of the camsurfaces 32, 34 is to continually increase the stiffness of the controllinks 24 as the deformable shell 16 and, thereby, the shell joints 30move in a downward direction and the frame joints 28 remain stationary.That is, the effective length of each of the bolster springs 24 iscontinually decreased as each spring bends along and comes into contactwith a larger portion of the cam surfaces 32, 34. The shape of the camsurfaces 32, 34 can thus be tuned to exhibit the desired rate ofincrease in spring rate for each spring. It is also noteworthy,particularly where both of the joints 28, 30 are constrained joints,that the ability of the deformable seat shell 16 to flex and changeshape accommodates the movement illustrated in FIGS. 2 and 3. In otherwords, a rigid seat pan without the flexibility of the deformable seatshell 16 would not allow the frame joint 28 and shell joint 30associated with one of the motion control links 24 to move closertogether in the loaded condition shown in FIG. 3 than they are in theunloaded condition of FIG. 2. The phantom line shown between the twodownward facing cam surfaces 34 schematically illustrates how a portionof the shape of the deformable shell may change when joints 28, 30undergo relative movement.

FIG. 4 shows a pair of the inner motion control links 26 of FIG. 1, eachwith a constrained frame joint 28 at one end and a pivot shell joint 30at the opposite end. In this case, the pair of motion control links 26include front and rear inner motion control links, and each may beconfigured with a unique spring rate, shape, joints, etc. FIG. 4 showsthe control links 26 in the relaxed or unloaded condition so that theyare generally flat and inclined with respect to horizontal. FIG. 5 showsthe control links 26 after corresponding frame and shell joints 28, 30undergo relative movement, such as when a seat occupant sits on theseat. Each control link 26 bends along a corresponding upward facing camsurface 32, as shown. The effect of the cam surfaces 32 is tocontinually increase the stiffness of the seating region springs 26 asthe deformable shell and, thereby, the shell joints 30 move in adownward and rearward direction and the frame joints 28 remainstationary. That is, the effective length of each of the control links26 is continually decreased as each bends along and comes into contactwith a larger portion of the corresponding cam surface 32. The shape ofthe cam surfaces 32 can thus be tuned to exhibit the desired rate ofincrease in spring rate for each spring. The cam surfaces 32 can also beconfigured to achieve the desired direction of movement of thedeformable seat shell with respect to the support frame. In FIGS. 1-5,each of the upward facing cam surfaces 32 is fixed in position relativeto the support frame 22, and each of the downward facing cam surfaces 34is fixed in position relative to the deformable seat shell 16, but thisneed not always be the case. Any of the cam surfaces 32, 34 may be fixedin position or may be configured to move with either of the supportframe 22 or the deformable seat shell 16 or with some other component,or they may be omitted entirely.

In FIG. 5, the unloaded position of the shell joints 30 is depicted inphantom. From the unloaded to the loaded positions, the shell joint 30moves in direction A, though not necessarily along a straight path. Theangle a represents the angle of a line formed between the loaded andunloaded positions of the shell joint 30. The angle a may range anywherefrom 0-90 degrees, but is preferably between 15 and 75 degrees. In oneembodiment, the angle α is between 30 and 60 degrees. In anotherembodiment, the angle α is about 45 degrees. Thus, when a seat occupantfirst sits on the seat, the deformable seat shell may move in downwardand/or rearward directions, with the reverse movement occurring when theoccupant vacates the seat. This type of movement can provide theoccupant with a sensation that the seat assembly is “pulling” theoccupant down into the seat and against the seat back for a more secureand comfortable feeling.

It is noteworthy that the movement of the outer motion control links 24and the movement of the inner motion control links 26, though shown asindependent movements in FIGS. 2-5, are not entirely independent. Thisis due to all of the frame joints 28 being fixed in position relative tothe support frame, and all of the shell joints 30 being fixed inposition relative to the deformable seat shell. The flexibility of thedeformable seat shell accommodates relative movement of the differentshell joints with respect to one another, and the otherwise predictable,uniform vertical movement provided by the depicted bolster springs 24 ifthey were acting alone, may be affected by the constraints on seat shellmovement due to the seating region springs 26.

Referring again to FIG. 1, some of the above-described components arefurther described as portions of other sub-components of the illustratedseat assembly 10. The seat assembly 10 includes a seat foundation 36adapted to be anchored to a vehicle floor. The seat bottom 12 is mountedon the seat foundation 36. The seat bottom 12 includes a variable-shapeseat pan 38 that is arranged to underlie and support a person that isseated on seat bottom 12. The variable-shape seat pan 38 includes theabove-described deformable seat shell 16 and is configured to changeshape in response to a shift in position or a change in posture of theseated person from an initial seat-pan shape to a subsequent seat-panshape. In this example, the seat bottom 12 includes the support frame 22(also referred to as a pan support frame in this case), the decorativeseat covering (not shown), and a frame shield (not shown). The seatcover may be coupled to the variable-shape seat pan 38, and the frameshield may be coupled to the support frame 22 to hide portions thereof.The support frame 22 is configured to be mounted on the underlying seatfoundation 36 to provide means for supporting the variable-shape seatpan 38 above the vehicle floor at all times and during a change in shapeto the variable-shape seat pan. It is within the scope of thisdisclosure to use any suitable support frame 22 on the seat foundation36 to support the variable-shape seat pan 38 for shape-changing movementrelative to the vehicle floor. It is also within the scope of thisdisclosure to mount the variable-shape seat pan 38 on the vehicle floor.In one embodiment, the vehicle floor is the support frame 22. Thesupport frame 22 may include one or more foundation support surfaces 40.In the example of FIG. 1, the support frame 22 includes left and rightsupport surfaces 40 that face upwardly toward the variable-shape seatpan 38 and away from the vehicle floor to mate with downwardly facingportions of the variable-shape seat pan 38 to support the seat pan onthe support frame.

With reference to FIG. 6, some more of the above-described componentsare further described as portions of other sub-components of the seatassembly 10 of FIG. 1. FIG. 6 is an exploded view of the variable-shapeseat pan 38 of FIG. 1. As shown, the seat pan 38 includes the deformableseat shell 16 and the shell motion controller 20, also referred to as acompliant shell motion controller in some cases. The shell motioncontroller 20 is coupled to the deformable seat shell 16 and isconfigured to mate with the foundation support surfaces of the supportframe. As described above, the deformable seat shell 16 may be formedfrom a deformable material and is able to change shape from a first seatshell shape to assume a plurality of seat shell shapes, including anillustrative second seat shell shape. In some embodiments, thedeformable seat shell 16 is made from an elastic and/or plasticmaterial. In some embodiments, the shell-motion controller 20 is madefrom the same material as the deformable seat shell 16 and cooperateswith the deformable seat shell to form the variable-shape seat pan 38.In some embodiments, the variable-shape seat pan 38 is monolithic. It iswithin the scope of this disclosure to overmold the deformable seatshell 16 onto separate first and second spring units similar in functionto the shell mounts described herein.

The illustrated shell motion controller 20 includes first and secondouter shell mounts 42 and an inner shell mount 44. The inner shell mount44 is positioned between the first and second outer shell mounts 42.Each shell mount 42, 44 is coupled to the deformable seat shell 16 andadapted to mate with the support frame or some other component that isstationary with respect to the vehicle floor. In this embodiment, eachouter shell mount 42 is coupled to opposite side portions 46 of thedeformable seat shell 16 and arranged to lie in spaced-apart relation(e.g., left-to-right) to with each other. The inner shell mount 44 iscoupled to a central or occupant-support portion 48 of the deformableseat shell 16 between the first and second outer shell mounts 42. Eachinner shell mount 44 in this example is configured to mate with thesupport frame 22 to support the deformable seat shell 16 forshape-changing movement relative to the vehicle floor or other seatassembly support surface. The illustrated inner shell mount 44 controlsmovement of the deformable seat shell 16 when an occupant sits on thedeformable seat shell 16 so that the seat shell moves down and to therear toward the seat back. In one example, the deformable seat shell 16moves about 50% down and 50% to the rear. In other words, about half ofthe movement is downward movement and about half of the movement isrearward movement (e.g. along a 45-degree angle).

The illustrated inner shell mount 44 includes left and right linkfoundations 50 and four inner motion control links 26. The left andright inner link foundations 50 are substantially similar in thisexample. The left and right link foundations 50 are coupled to andarranged to lie in a stationary or fixed position on the support frame.One end of each of two of the motion control links 26 is coupled to eachlink foundation 50 in spaced-apart relation (e.g. front-to-rear) to formthe constrained frame joints, and an opposite end of each of the twomotion control links is coupled to the central portion 48 of thedeformable seat shell 16 at an opposite end to form the pivot shelljoints. As shown in FIG. 6, each exemplary inner link foundation 50includes first and second foundation plates 52. Each pair of plates, 52is coupled together to trap the motion control links 26 therebetween.Each of the illustrated inner link foundations 50 is formed to includethe upward facing cam surfaces 32 described above—one for eachassociated motion control link 26. When the deformable seat shell 16 isin the unloaded condition, control links 26 extend between thedeformable seat shell 16 and the associated link foundation at about a45 degree angle with respect to horizontal. When the deformable seatshell 16 is in a loaded condition, the motion control links 26 bendtoward the seat back to engage and conform to the corresponding camsurfaces 32, as shown for example in FIG. 5.

Each of the inner link foundations 50 may be constructed from a plasticmaterial or from any suitable alternative. In one embodiment, the motioncontrol links 26 are constructed from a metal material, such as springsteel, but may be made from any other suitable material such as anelastic, deformable plastic material or composite. Each motion controllink 26 may be allowed to flex and/or to change in orientation (e.g.slope), shape, and/or length to support a change in shape of thedeformable seat shell 16 during exposure of the variable-shape seat pan38 to external forces applied to the deformable shell by the seatoccupant as he or she person shifts position or changes posture on theseat bottom 12 or is acted upon by inertial forces.

The inner motion control links 26 are included with the illustratedinner shell mount 44 and cooperate to provide means for yieldablysupporting the deformable seat shell 16 for controlled movement relativeto the left and right inner link foundations 50, which in this case arefixed relative to the support frame and vehicle floor, in response toforces applied by the seat occupant to the deformable seat shell. In theillustrated embodiment, the initial orientations of the control links 26support the deformable seat shell 16 in a first or undeformed (unloaded)seat shell shape with relatively steep positive slopes with respect tohorizontal. In contrast, the final or loaded orientations of the motioncontrol links 26 change after the deformable seat shell 16 has beenmoved to assume a second or deformed (loaded) seat shell shape. Whenloaded, the control links 26 have a relatively lower positive slope thanwhen unloaded and generally conform to the cam surfaces 32.

Each outer shell mount 42 of FIG. 6 is configured to mate with afoundation support surface of the support frame to support thedeformable seat shell 16 for shape-changing movement relative to thevehicle floor, ground, or other seat assembly support surface. The outershell mounts 42 control movement of opposite first and second sideportions 46 of the deformable seat shell 16 when an occupant sits on thedeformable shell 16 so that the opposite side portions 46 of the seatshell move generally vertically. Each outer shell mount 42 in thisexample includes a link foundation 54 and two outer motion control links24. Each link foundation 54 is coupled to and arranged to lie in astationary or fixed position relative to the support frame. Each of themotion control links 24 is coupled at one end to a corresponding linkfoundation 54 and at an opposite end to a side portion 46 of thedeformable seat shell 16. Each outer shell mount 42 may be made of metalor any other suitable material such as an elastic, deformable plasticmaterial. The motion control links 24 may also be made of metal or anyother suitable material, such as an elastic, deformable plasticmaterial. Each motion control link 24 may be configured to flex and/orchange orientation (e.g. slope), shape, and/or length to support achange in shape of the deformable seat shell 16 during exposure of thevariable-shape seat pan 38 to external forces applied to the seat shell16.

In the illustrated example, each link foundation 54 includes a linkanchor strip 56 and an anchor mount 58 coupled to the anchor strip andarranged to extend downwardly toward the support frame. The link anchorstrip mates with the underlying foundation support surface of thesupport frame 22. The anchor mount 58 is adapted to be coupled to anearby portion of the support frame 22 to hold the anchor strip 56 inmating engagement with the foundation support surface.

The outer motion control links 24 included with each outer shell mount42 cooperate to provide means for yieldably supporting the deformableshell 16 for controlled movement relative to the link foundation 54. Theinitial orientations of the control links 24 support the deformable seatshell 16 in a first seat-shell shape. For example, relative to theunderlying link anchor strip 56, each control link 24 has a relativelyflat, horizontal slope. The orientations of the motion control links 24change after the deformable seat shell 16 has been moved to assume asecond seat-shell shape. For example, relative to each of the underlyinglink anchor strips 56, some of the motion control links 24 (i.e., theforward-most ones) assume one slope, and some of the motion controllinks (i.e., the rear-most ones) assume an opposite slope. As a result,and as depicted by way of example in FIGS. 2 and 3, the side portions 46of the deformable seat shell 16 are constrained to move generallyvertically relative to the associated link foundation 54, which is fixedin location relative to the support frame 22 and the vehicle floor.

As noted above, the deformable seat shell 16 includes central portion 48arranged between and interconnecting opposite first and second sideportions 46. In the illustrated embodiment, the central portion 48includes a buttocks-support section 60, and left and right leg supportsections 62. The central portion 48 may include a slot or cleave 64, asshown, located between forward portions of the leg sections 62 to freethose sections for limited relative movement under loads applied by aseat occupant. The slot 64 is centrally located and enables the legsupport sections 62 to simultaneously deform or flex by differentamounts from each other during shape-changing movement of the seat shell16. The buttocks-support section 60 may be somewhat bowl-shaped, asshown, and may be formed to include several generally laterallyextending slots 18 to enhance the deformability and shape-changingcharacteristics of the central portion 48.

An embodiment of the seat assembly is illustrated in FIG. 7 in anexample of use. A seat occupant is shown seated on the seat bottom 12,which includes the variable-shape seat pan 38 with the deformable seatshell 16. The seat pan 38 is configured to provide means for maintainingthe pelvis (P) of the seat occupant in engagement with the seat back 14to lessen, minimize, or eliminate pelvis drift and thereby increase,maximize or provide occupant comfort. As shown in FIG. 7, the lower bodyof the seat occupant includes a lumbar spine region (LS), pelvis (P),ischia (I), and femur (F). Pelvis drift occurs when the pelvis slidesaway from the seat back 14 over time during use, such as during vehicleoperation or office task performance, so that the pelvis is spaced awayfrom the seat back. An example of pelvis drift is shown in FIG. 8, wherethe occupant is seated on a traditional seat pan. Pelvis drift isreduced and/or minimized as a result of the shell motion controller andassociated motion control links controlling movement of the deformableseat shell 16 so that it moves downwardly and rearwardly toward the seatback 14, as shown in FIG. 7.

The above-described variable-shape seat pan 38 may also be configured tochange in width in response to various sized occupants sitting on theseat assembly. FIG. 9 schematically shows front views of various shapesthe deformable seat shell 16 may assume with different sized occupants.An unloaded or unoccupied condition of the deformable seat shell 16 isindicated in FIG. 9 as a dashed line (U). A first loaded condition isindicated in FIG. 9 as a dotted line (S), where a small seat occupant isseated on the deformable shell 16. The small occupant has a small widthand is primarily supported by the central portion 48 of the deformableshell 16. As a result, relatively little force is transferred to theside portions 46 of the deformable shell so that they have relativelylittle downward movement. A second loaded condition is indicated in FIG.9 as a solid line (L), where a large seat occupant is seated on thedeformable shell 16. The large occupant has a large width and issupported by both the central portion 48 and the side portions 46 of thedeformable shell 16. As a result, force is transferred to the side andcentral portions 46, 48 of the seat shell 16. Force transferred to theside portions 46 cause them to move down to create a relatively largerwidth for supporting the large occupant. Thus, a passive seat-widthadjustment is provided. The shell motion controller and associatedmotion control links can be configured to provide a variable-widthseating surface that is capable of supporting the 95th percentile maleand the 5th percentile female and all sizes of occupants therebetween.

The variable-shape seat pan 38 can also be configured to provide apassive tilt function, where the rear-most portion of the deformableseat shell 16 moves down more than the front-most portion when changingshape from the unloaded to loaded condition. Such shape-changingmovement can cause the knees of the seat occupant to be raised upwardlyaway from the vehicle floor as the bottom of the occupant is lowereddownwardly toward the floor and rearward toward the seat back. When thedeformable seat shell 16 has been moved to assume the second (loaded)seat shell shape, the motion control links have also moved to assume newshapes or slopes. Thus, the variable-shape seat pan 38 may be configuredand arranged to replace a traditional tilt function of the seat assemblyto minimize seat weight and cost. This passive tilt function is suchthat the amount of tilt can change with changing load distribution fromthe seat occupant, such as during occupant-initiated posture or positionchanges, inertial forces, or when a smaller or larger occupant issitting on the seat.

FIGS. 10-12 illustrate a portion of another embodiment of theabove-described seat assembly. The illustrated portion is thevariable-shape seat pan 138, shown in a front-bottom view in FIG. 10, ina front-top view in FIG. 11 (with the outline of the deformable seatshell 116 in phantom), and in an exploded view in FIG. 12. The shellmotion controller 120 includes differently configured outer motioncontrol links 124 and inner motion control links 126. In particular,each of the inner control links 126 in this example is an elongatemember extending along a side-to-side direction with respect to the seatassembly between a pivot frame joint 128 and a constrained shell joint130. Each of the outer control links 124 extend along the front-to-backdirection with respect to the seat assembly. This embodiment includesfour inner motion control links comprising two pair of control links(front and rear pairs), with each pair being formed from a single stripof material that extends between opposite left and right pivot framejoints 128, located on opposite left and right sides of the seat. Eachpair of inner motion control links shares a constrained shell joint 130,located centrally with respect to the seat. In this example, each of thefour outer motion control links 124 are formed from separate strips ofmaterial.

Each frame joint 128 has a fixed position relative to the support frame122, and each shell joint 130 has a fixed position relative to thedeformable seat shell 116. Each motion control link has a correspondingframe joint 128 and shell joint 130 and allows the pair of joints tomove with respect to each other while also constraining their relativemovement. Here again, each motion control link is configured as a flatspring that undergoes elastic deformation when the corresponding frameand shell joints 128, 130 undergo relative movement. Each of the controllinks is a strip of material that bends in a direction parallel with thedirection of the thickness of the strip of material when thecorresponding joints 128, 130 undergo relative movement. The resultingmovement of this configuration is somewhat different from that of theembodiment depicted in FIGS. 1-6 while maintaining at least some of theadvantages depicted in FIGS. 7-9.

FIGS. 13-16 are simplified schematic views illustrating the constrainedrelative motion associated with each of the motion control links 124,126 depicted in FIGS. 10-12. FIG. 13 is a side view of one pair of theouter motion control links 124, each with a constrained frame joint 128at one end and a constrained shell joint 130 at the opposite end. Inthis case, each of the outer motion control links 124 is formed from aseparate piece of material so that the control links have separate framejoints 128 and shell joints 130. Each control link may be configuredwith a unique spring rate, shape, joint, etc. FIG. 13 shows the controllinks 124 in a relaxed or unloaded condition in which they are generallyflat. FIG. 14 shows the control links 124 after corresponding frame andshell joints 128, 130 undergo relative movement, such as when a seatoccupant sits on the seat. Each motion control link 124 bends alongupward facing and downward facing cam surfaces 132, 134, as shown. Oneeffect of the cam surfaces 132, 134 is to continually increase thestiffness of the control links 124 as the deformable shell 116 and,thereby, the shell joints 130 move in a downward direction and the framejoints 128 remain stationary. That is, the effective length of each ofthe bolster springs 124 is continually decreased as each spring bendsalong and comes into contact with a larger portion of the cam surfaces132, 134. The shape of the cam surfaces 132, 134 can thus be tuned toexhibit the desired rate of increase in spring rate for each spring. Asnoted above, the ability of the deformable seat shell 116 to flex andchange shape accommodates the illustrated movement.

FIG. 15 shows the inner motion control links 126, each with a pivotframe joint 128 at one end and a constrained shell joint 130 at theopposite end. Each individual or pair of motion control links 126 may beconfigured with a unique spring rate, shape, joints, etc. FIG. 15 showsthe control links 126 in the relaxed or unloaded condition so that theyare generally flat with the widthwise direction of each strip ofmaterial inclined with respect to horizontal, by about 45 degrees, forexample. The pivot axes for the pivot joints 128 are inclined withrespect to the horizontal by about the same angle, shown in FIG. 15 asan angle of inclination β.

FIG. 16 is a cross-sectional view of one pair of the control links 126of FIG. 16 taken perpendicular to the thickness of the control links.The top of FIG. 16 shows the unloaded condition, and the bottom of FIG.16 shows a loaded condition after the frame and shell joints 128, 130undergo relative movement, such as when a seat occupant sits on theseat. Each control link 126 bends along a corresponding downward facingcam surface 134, as shown. The deformable shell and, thereby, the shelljoints 130 move in a downward and rearward direction, while the framejoints 128 remain stationary. As each control link 126 bends, it comesinto contact with a larger portion of the corresponding cam surface 134.The shape of the cam surfaces 134 can be tuned to exhibit the desiredrate of increase in spring rate for each link 126. The cam surfaces 134and the angle of inclination β of the width of the strip of materialand/or the pivot axes of joints 128 can be configured to achieve thedesired direction of movement of the deformable seat shell with respectto the support frame. The direction of movement in this example isgenerally perpendicular to the thickness direction of the control links126 (parallel with the direction of bending). Stated differently, thedirection of movement is generally at an angle of β−90°, where 0°>β>90°.The angle of inclination β may range anywhere is preferably between 15and 75 degrees. In one embodiment, the angle β is between 30 and 60degrees. In another embodiment, the angle β is about 45 degrees.

Thus, when a seat occupant first sits on the seat, the deformable seatshell may move in downward and/or rearward directions, with the reversemovement occurring when the occupant vacates the seat, similar topreviously described embodiments. Here again, it is noteworthy that themovement of the outer motion control links 124 and the movement of theinner motion control links 126, though shown as independent movements inFIGS. 13-16, are not entirely independent due to all of the frame joints128 being fixed in position relative to the support frame, and all ofthe shell joints 130 being fixed in position relative to the deformableseat shell. The flexibility of the deformable seat shell accommodatesrelative movement of the different shell joints with respect to oneanother, and the otherwise predictable, uniform vertical movementprovided by the depicted bolster springs 124 if they were acting alone,may be affected by the constraints on seat shell movement due to theseating region springs 126.

With reference again to the exploded view of FIG. 12, some of thecomponents of this particular embodiment of the seat pan 138 are furtherdescribed. As shown, the seat pan 138 includes the deformable seat shell116 and the shell motion controller 120, which may also be referred toas a compliant shell motion controller in some cases. The shell motioncontroller 120 is coupled to the deformable seat shell 116 and isconfigured to mate with foundation-support surfaces of the support frame(not shown). The illustrated shell motion controller 120 includes firstand second outer shell mounts 142 and an inner shell mount 144. Theinner shell mount 144 extends generally between the first and secondouter shell mounts 142, but could be located between or extend to jointsoutside of the outer shell mounts 142.

In this embodiment, each outer shell mount 142 is coupled to oppositeside portions 146 of the deformable seat shell 116 and arranged to liein spaced-apart relation (e.g., left-to-right) with each other. Theinner shell mount 144 is coupled to a central or occupant-supportportion 148 of the deformable seat shell 116 between the first andsecond outer shell mounts 142. Each shell mount 142, 144 is configuredto mate with the support frame to support the deformable seat shell 116for shape-changing movement relative to the vehicle floor or other seatassembly support surface. The illustrated inner shell mount 144 controlsmovement of the deformable seat shell 116 when an occupant sits on thedeformable seat shell so that the seat shell moves down and to the reartoward the seat back. The deformable seat shell 116 may be configured tomove about 50% down and 50% to the rear, or along about a 45-degreeangle.

The illustrated inner shell mount 144 includes left and right linkfoundations 150 and four inner motion control links 126. The left andright link foundations 150 are coupled to and arranged to lie in astationary or fixed position on the support frame, and each has aportion that extends inwardly toward the other where the respectivepivot frame joints are formed. One end of each of the motion controllinks 126 is pivotally coupled to one of the link foundations 150 toform the pivot frame joints, and an opposite end of each of the motioncontrol links is coupled to the central portion 148 of the deformableseat shell 116 to form the constrained shell joints. In this particularexample, the shell joints are formed via an inner shell supportstructure 166. The inner shell support structure 166 is coupled withfront and rear pairs (i.e., strips) of motion control links 126 andprovides the downward facing cam surfaces 134 for the inner shell mount.The width of each cam surface 134 is inclined with respect to thehorizontal at about the same angle as each motion control link 126 tomate therewith. The illustrated inner shell support structure 166extends between and interconnects front and rear pairs of motion controllinks 126. The inner shell support structure 166 may also provide somesupport and structure to the deformable seat shell 116.

In this example, the support structure 166 further includes stiffeningportions 168, 170. Each stiffening portion 168, 170 is a wall or ribextending along the lengthwise edge of each cam surface 134 andgenerally perpendicular with each cam surface. In this example, one ofthe stiffening portions 168 extends away from the corresponding camsurface in one direction (i.e., upward and frontward), and the other ofthe stiffening portions 170 extends in the opposite direction (i.e.,downward and rearward). These stiffening portions 168, 170 may beprovided to limit or prevent flexing or bending of the cam surfaces 134when under load so that the shape of the cam surfaces remains relativelyconstant, and they may be particularly useful where the supportstructure is formed from a relatively flexible material, such as aplastic material. The illustrated support structure 166 also includesspine members 172 that extend in the front-to-rear direction andinterconnect each cam surface 134—and its associated stiffening portions168, 170—with the other. The illustrated spine members 172 also act asstiffening members or beams that provide structure along the centralportion 148 of the seat shell 116. In this embodiment, the supportstructure 166 is monolithic and separately formed from the seat shell.In other embodiments, the shell 116 and support structure 166 may beformed as a monolithic structure, or a portion of the support structure166, such as the cam surfaces 134, stiffening portions 168, 170 and/orspine members 172, may be formed together with the seat shell 116 as amonolithic structure. Or one or more portions of the support structure166 may be omitted entirely.

In the illustrated embodiment, the left and right link foundations 150also provide joint forming portions for the outer shell mounts 142. Inparticular, each of the link foundations 150 includes a link anchorstrip 156. In this example, one end of each outer motion control link124 attaches to the bottom or underside of the link anchor strip 156 toform a constrained joint. Each anchor strip 156 includes a snubberportion 174 that overlies or covers a portion of each motion controllink 124 to prevent the covered portion from deflecting in an upwarddirection. As with previous embodiments, each of the link foundations150 may be formed from mating foundation plates 152. In the illustratedexample, the plates 152 are arranged to attached to opposite left andright sides of a support frame for the seat assembly.

The upward facing cam surfaces 132 may be provided by the support frameor by some other component attached to the support frame of the seat. Inthis example, the upward facing cam surfaces 132 are provided by thelink foundations 150. In this particular embodiment, cam surfaces 132are relatively small in width in relation to the motion control links124 and may be in the form of an edge surface as shown. The downwardfacing cam surfaces 134 of the outer shell mounts 142 are provided byouter shell support structures 175. These outer shell support structures175 may be formed as separate pieces as shown, or they may be formedmonolithically with the seat shell 116. In this example, each outershell support structure 175 is affixed to and is fixed in positionrelative the deformable seat shell 116 so that the downward facing camsurfaces 134 and the associated constrained shell joints are fixed inposition relative to the seat shell. The illustrated combination ofcomponents for the shell motion controller 120 can provide constrainedrelative motion of the deformable seat shell and the support frame withwhich it is coupled by the shell motion controller.

FIGS. 17-21 illustrate some of the possible assembly steps forconstructing a seat bottom 212 in accordance with another embodiment.This embodiment combines outer motion control links or bolster springs224 similar to those depicted in FIGS. 1-6 with inner motion controllinks or cross-springs 226 similar to those depicted in FIGS. 10-16.FIG. 17 is a front bottom view of the deformable seat shell 216 showingportions of the shell motion controller being assembled thereto. In thisexample, spine members 272 are formed monolithically as part of the seatshell 216 and include attachment features (e.g., staking posts) 276extending therefrom for attachment of cross-spring cams 278.Corresponding attachment features 280 of the cross-spring cams 278 arealigned with the shell features 276 for assembly. In this case,apertures 280 formed through the cross-spring cams 278 receive stakingposts 276 of the seat shell 216, and the posts are flattened (e.g., byheat, pressure and/or ultrasonic staking) to attach the cams 278 to theseat shell. Other attachment feature pairings are possible (snapfeatures, hole/fastener, etc.) and the attachment features may beomitted entirely in some cases.

Each of the cross-spring cams 278 includes a downward facing cam surface234 (facing upward in FIG. 17 because the seat shell is inverted) andstiffening portions 268, 270. Each cross-spring cam 278 may be formedfrom a single piece of sheet metal or other suitable material. Wheremetal is employed, it may be possible to reduce the size or length ofthe stiffening portions when compared to plastic. The particular cams278 shown in FIG. 17 include auxiliary openings 282, which may beincluded for weight-reduction, ease of manufacturing, or for otherreasons. The cam surface(s) 234 may include a layer of sound-attenuatingmaterial, such as an elastomeric material (e.g., rubber) to help isolatethe cam surface from the inner motion control links. This may beparticularly useful where one or both of the cam surface 234 and thecross-spring are metal. An adhesive-backed layer of 1/16-inch rubber issuitable, but other materials may be used. For example, a thermoplasticelastomer (TPE) may be overmolded on the cam surface 234, or a spray-oncoating may be employed.

FIG. 18 illustrates the outer motion control links or bolster springs224 arranged for attachment to the outer support structure or bolsteredge frame 275. In this example, similar to the embodiment of FIGS. 1-6,two motion control links 224 are formed as a single strip of material.The single strip of material may be referred to as a side or bolsterspring with independently deflectable opposite ends. Fasteners such asrivets, bolts, etc. are shown here forming constrained shell joints 230,with additional apertures provided near the center of the strip ofmaterial for formation of frame joints with a frame support or otherstructure. The support structure 275 includes downward facing camsurfaces 234 for each spring 224 and attachment features 276 (e.g.,snap-in features) for attaching the structure 275 to the seat shell 216.In one embodiment, the support structure 275 is formed from sheet metalhaving a thickness of about 0.050 inches. Other materials such asplastic or plastic composite materials (e.g., glass-filled polyamide)may be used as well.

FIG. 19 illustrates the support frame 222, including upward facing camsurfaces 232 for the bolster springs. Here, the inner motion controllinks 226 are provided in pairs, with each pair being formed from asingle strip of material that extends between opposite left and rightsides of the support frame 222. Each pair of inner motion control links226 may together be referred to as a cross-spring. Front and rearcross-springs are coupled with the support frame by pins 284 to formpivot frame joints at opposite ends of each cross-spring. In thisexample, a layer of sound-attenuating material 286 is provided with eachcross-spring and oriented to face toward the cam surfaces of thecross-spring cams. As noted above, the layer 286 may alternatively oradditionally be provided as an attachment to the cam surface itself. Asshown, apertures may be provided near the center of each cross-springfor attachment to the cross-spring cams and formation of the constrainedshell joints.

FIG. 20 shows the bolster springs 224, together with bolster snubbers274, being attached to the upward facing cam surfaces 232 of the supportframe 222. The snubbers 274 are provided to inhibit upward motion of thebolster springs to avoid a “rocking” feel to the bolster motion. Forexample, without snubbers 274, placing a downward load on the frontportion of the bolster region of the seat bottom can cause a rearwardportion of the bolster region to lift or raise. The snubbers 274 may beformed as a separate piece of sheet metal, as shown here, or may beintegrated as a portion or extension of some other component. Once thebolster springs are in place, the subassembly of FIG. 17 can be placedover the cross-springs and outer shell supports 275 and attachedthereto. The attachment features 276 of the outer shell supports 275 maysnap into openings formed in the side walls of the deformable seat shell216, and fasteners or other suitable attachment means may be used toattach the cross-spring cams 278 to the cross-springs. FIG. 21 shows thefinished seat bottom 212 (without a decorative covering or frame coversor panels). The example of FIGS. 17-21 is illustrative only, as the seatcomponents may be assembled in any order and may include additionalcomponents or omit certain components consistent with the teachingspresented herein. For example, the outer support structures 275, bolstersprings and/or cross-springs could be assembled to the deformable seatshell before being attached to the support frame.

In other variations, the above-described sound-attenuating layer 286 maybe included along one or both opposite sides of the bolster springsand/or the cam surfaces associated therewith. In one embodiment, theupward and downward facing cam surfaces of the outer shell mount aremetal, and a sound-attenuating layer is provided between the bolsterspring and one or both of the cam surfaces. While each of the motioncontrol links in the figures is in the form of a strip of material thatacts as a flat spring that bends along a cam surface, other motioncontrol links are possible and the cam surfaces are optional. Forexample, a motion control link may be in the form of a rigid rod or anassembly of rigid rods configured to link a given frame joint to a givenshell joint and to allow constrained relative movement thereof. Suchcontrol links may be acted upon by a spring or other biasing member.Other types of springs may be used instead of or in addition to theillustrated flat springs, such as coil springs, torsional springs, leafsprings, belleville washers, etc.

Where springs are used as motion control links, metal strips may bepreferred due to their resilience to relaxation over time when comparedto non-metallic materials such as polymeric materials. In one example,the cross-springs are formed from spring steel having a thicknessbetween 0.050 inches and 0.0625 inches, but thickness may vary dependingon the desired movement characteristics, material choice, etc. Thespring material may be heat-treated as well. Similar materials may beused for the bolster springs. In one embodiment, each cross-springincludes bushings or other bearing surfaces at its opposite ends forformation of pivot frame joints. For example, each end of thecross-springs may include a cylindrical portion that receives the pins284 of FIG. 19 and provides an inner bearing surface that interfaceswith the outer surface of each pin for pivoting movement. Such acylindrical portion may be a low-friction plastic material (e.g.,acetal, nylon, etc.) and may be overmolded or otherwise attached to thestrip of material that makes up the flexible portion of the controllink. The ends of each cross-spring could also be formed by bending theends into the desirable shape.

In yet another variation, a dashpot or other type of motion-dampingmechanism is operatively connected between the deformable seat shell andthe support frame to affect the rate of elastic motion of the motioncontrol links. For example, in the embodiment depicted in FIGS. 17-21,one end of the damping mechanism may be coupled with a cross-spring cam,and an opposite end of the damping mechanism may be coupled with thesupport frame, such as a cross-member extending between left and rightsides of the support frame.

A seat assembly constructed in accordance with the teachings herein mayhave a comfort feel similar to or superior to that of traditional rigidseat pans topped with polyurethane or other foam materials. A seatbottom including the deformable seat shell described above, when coupledwith the shell motion controller configured as taught herein, may reduceor eliminate the need for bulky and environmentally-challenging foambuns or cushions, while providing a lower-profile (small packaging)design and increasing occupant comfort by properly maintaining theoccupant's pelvis and lumbar region near the seat back and preventingpelvis drift. In one embodiment, the deformable seat shell isconstructed from a recyclable thermoplastic material.

It is to be understood that the foregoing is a description of one ormore preferred exemplary embodiments of the invention. The invention isnot limited to the particular embodiment(s) disclosed herein, but ratheris defined solely by the claims below. Furthermore, the statementscontained in the foregoing description relate to particular embodimentsand are not to be construed as limitations on the scope of the inventionor on the definition of terms used in the claims, except where a term orphrase is expressly defined above. Various other embodiments and variouschanges and modifications to the disclosed embodiment(s) will becomeapparent to those skilled in the art. All such other embodiments,changes, and modifications are intended to come within the scope of theappended claims.

As used in this specification and claims, the terms “for example,” “forinstance,” “such as,” and “like,” and the verbs “comprising,” “having,”“including,” and their other verb forms, when used in conjunction with alisting of one or more components or other items, are each to beconstrued as open-ended, meaning that that the listing is not to beconsidered as excluding other, additional components or items. Otherterms are to be construed using their broadest reasonable meaning unlessthey are used in a context that requires a different interpretation.

The invention claimed is:
 1. A seat assembly, comprising: a seat bottomhaving a deformable seat shell configured to change shape with achanging occupant load distribution; a motion control link coupling thedeformable seat shell with a support frame via a frame joint and a shelljoint so that said joints can undergo relative movement, the frame jointbeing at a fixed position relative to the support frame and the shelljoint being at a fixed position relative to the deformable seat shell,wherein the motion control link constrains said relative movement; and acam surface, wherein the motion control link elastically bends along thecam surface when said joints undergo relative movement, at least one ofthe joints being a constrained joint at the cam surface.
 2. A seatassembly as defined in claim 1, wherein the motion control link is aspring, wherein the stiffness of the spring continually increases as thespring bends and comes into contact with a larger portion of the camsurface.
 3. A seat assembly as defined in claim 1, wherein said camsurface is fixed with respect to the deformable seat shell.
 4. A seatassembly as defined in claim 1, wherein said cam surface is fixed withrespect to the support frame.
 5. A seat assembly as defined in claim 1,further comprising a layer of sound-attenuating material located betweenthe motion control link and the cam surface when the motion control linkelastically bends along the cam surface.
 6. A seat assembly as definedin claim 1, wherein the cam surface is a first cam surface located onone side of the motion control link and the seat assembly furthercomprises a second cam surface located on an opposite side of the motioncontrol link, wherein the motion control link elastically bends alongboth cam surfaces when said joints undergo relative movement.
 7. A seatassembly as defined in claim 1, wherein the other one of the joints is aconstrained joint.
 8. A seat assembly as defined in claim 1, wherein themotion control link is an elongate member extending along afront-to-rear direction with respect to the seat assembly.
 9. A seatassembly as defined in claim 1, wherein the motion control link is anelongate member extending along a side-to-side direction with respect tothe seat assembly.
 10. A seat assembly as defined in claim 1, whereinthe motion control link is a flat spring.
 11. A seat assembly as definedin claim 10, wherein the direction of the width of the flat spring isinclined with respect to horizontal.
 12. A seat assembly as defined inclaim 1, further comprising a second motion control link coupling thedeformable seat shell with the support frame via a second frame jointand a second shell joint so that said second joints can undergo relativemovement, the second frame joint being at a fixed position relative tothe support frame and the second shell joint being at a fixed positionrelative to the deformable seat shell, wherein the second motion controllink constrains said relative movement of said second joints.
 13. A seatassembly as defined in claim 12, wherein the motion control linksinclude at least one bolster spring that bends along the cam surface inone direction and along another cam surface in another oppositedirection when the deformable seat shell and the support frame undergorelative movement.
 14. A seat assembly as defined in claim 12, whereinthe cam surface is an inclined cam surface and the motion control linksinclude at least one cross-spring that bends along the inclined camsurface so that the deformable seat shell moves in downward and rearwarddirections relative to the support frame when an occupant sits on theseat assembly.
 15. A seat assembly as defined in claim 1, wherein thedeformable seat shell includes left and right leg support sectionsseparated by a centrally located slot that allows said support sectionsto simultaneously deform by different amounts from each other.
 16. Aseat assembly as defined in claim 1, wherein the deformable seat shellis made from a semi-rigid plastic material and includes a plurality ofslots formed through the plastic material that provide the deformableplastic shell with shape-changing flexibility so that the deformableshell can change shape in response to the changing occupant loaddistribution, the shell joint being formed along the semi-rigid plasticmaterial.
 17. A seat assembly as defined in claim 1, wherein the motioncontrol link is one of a pair of outer motion control links, the seatassembly further comprising a pair of inner motion control links, eachone of the control links being coupled with the deformable seat shell ata respective shell joint and with the support frame at a respectiveframe joint, wherein the shell and frame joints of the outer motioncontrol links are located at left and right bolster regions of the seatbottom and the shell joints of the inner motion control links arelocated at a seating region between said bolster regions.
 18. A seatassembly as defined in claim 17, wherein each one of the shell jointsand the frame joints of the outer motion control links is a constrainedjoint.
 19. A seat assembly as defined in claim 17, wherein each one ofthe shell joints of the inner motion control links is a constrainedjoint and each one of the frame joints of the inner motion control linksis a pivot joint.
 20. A seat assembly as defined in claim 17, whereineach one of the shell joints of the inner motion control links is apivot joint and each one of the frame joints of the inner motion controllinks is a constrained joint.